Switching and protection devices for high-voltage onboard electrical systems are used to manage the nominal current and a potential temporary overcurrent of the high-voltage onboard electrical system. All poles of the high-voltage onboard electrical system may be disconnected via the switching device during each switch-off process. However, the protection device is used for disconnecting a high-voltage battery in the case of fault currents which are larger than the overcurrents. The protection devices are generally designed as fuses. The switching devices may be designed as DC-voltage switches, for example, a relay. In the case of disconnections of all poles, disclosed embodiments are also possible in which one switching device is designed as a relay and one switching device is designed as a power semiconductor.
The fuses generally used are hermetically sealed fuses having ceramic or plastic housings in which multiple fusible elements having defined narrow sections are connected in parallel. Optionally, the housings are also filled with an extinguishing medium, for example, sand.
In addition to the resulting non-negligible installation space for the fuses, the requirements in a high-voltage onboard electrical system for motor vehicles place high demands in particular with respect to the triggering characteristics. For example, the allowable overcurrents may be relatively high. In addition, due to the parallel connection, manufacturing-related component tolerances must be considered, thus increasing the break times to be achieved.
Disclosed embodiments provide a switching and protection device which requires less installation space.